1. Field of the Invention
The present invention relates to a plastic casing with a conductive film for housing electronic instruments and to a method of making same, and is more specifically concerned with a method of making a plastic casing having the function of screening electromagnetic waves and preventing electrification.
2. Description of the Prior Art
In general, plastic casings for housing electrical instruments are imparted conductivity to screen electromagnetic waves and to prevent electrification. Such conductivity has been created mainly by coating surfaces of the casing with a conductive coating film. Such a process of coating a conductive material has been widely employed, as it is advantageous in the viewpoint of equipment costs, manpower, etc. Such a process, however, has difficulties in that it requires treatments for the solvent contained in the coating material which may cause breakage or discoloration of the final coating film, and an additional coating to ensure adhesion and prevent removal of the coating film. Further, most of coarse conductive powders contained in the coating material are contacted point-to-point or through a binder, thereby reducing conductivity and the effect of screening electromagnetic waves.